Pentagon report reveals the F-35 faults found by test engineers

The annual report from the Office of the Director of Operational Test and Evaluation (DOT&E) at the Pentagon has highlighted a number of faults with the F-35 fighter and its development and test program.

The DOT&E watchdog independently tests and evaluates US Defense equipment to ensure it is combat-ready.

The report from Robert Behler, director of the Operational Test and Evaluation Office, says that despite the deletion of test points, delays continue to affect the program: “Continued test delays, particularly for mission systems and F-35B flight sciences, will likely push the end of developmental testing into the first or second quarter of 2018, even as time and funding are running out for system development and demonstration.”

The F-35 single-seat jet fighter is being produced in three variants: the F-35A conventional take-off and landing variant, the F-35B short take-off/vertical landing variant, and the F-35C carrier variant.

Although F-35A flight testing was completed in March 2017 (with the exception of drag chute testing – a Norway-unique test requirement), F-35B testing has proved more challenging.

The report found that delays to testing of the F-35B were caused by the need for test-unique tail coatings, to prevent overheating of the horizontal tails at high airspeed test points; the repairing of unanticipated cracks in the main landing gear and structural frame; and engine restrictions that prohibit some flight operations.

Extra work that had to be carried out for the F-35C flight tests included the testing of the redesigned outboard wing structure, which was required to support the carriage of the AIM-9X air-to-air missile on a pylon.

Static structural and durability testing of the F-35A was completed in October 2017 and for the F-35C in 2018. The aircraft are tested for the equivalent of 24,000 hours of flight.

Durability testing for the F-35B was suspended after 16,000 hours in February 2017, because “the test article had so many repairs it was no longer representative of the production aircraft,” the report states.

“The effect of the failures observed and repairs required during the first two lifetimes of testing on the service life certification of the F-35B aircraft is still to be determined.

“The service life for all three variants is planned to be 8,000 hours, however the F-35B service life may be less than that, even with extensive modifications to strengthen the aircraft already produced.”

The report also identifies that “open deficiencies” have been found in the aircraft’s software, and that there are also problems with its weapons systems.

The F-35 program, which is estimated to cost approximately US$1.5tn, is the most expensive weapon ever-developed. The aircraft is being developed and acquired by several countries and the aircraft’s cost has been slammed by politicians around the world.

The F-35’s first flight was in 2006. The F-35B entered service in July 2015, the F-35A in August 2016 and F-35C is expected to enter service this year.

To date, more than 265 F-35 aircraft are operating from 14 bases worldwide and the fleet has surpassed more than 120,000 cumulative flight hours.

In response to the DOT&E report, Lockheed Martin said in statement that they are “confident in the F-35’s transformational capability that continues to be demonstrated through the steady progress in development, production and sustainment operations”.

It added, “The F-35 weapons system reliability continues to improve lot over lot and newer jets are averaging greater than 60% availability, with some operational squadrons consistently at or above 70% availability.

“Increased system reliability together with upgraded diagnostics in the latest Block 3F software have enabled significant improvement in aircraft availability. The plan is to retrofit these upgrades into earlier production aircraft.”

About Author

Ben has worked all of his career as a journalist and now editor, covering almost all aspects of technology, engineering and industry. In the last 16 years he has written on subjects from nuclear submarines and autonomous cars to future design and manufacturing technologies and commercial aviation. Latterly editor of a leading engineering magazine, he brings an eye for a great story and lots of experience to the team.